Adsorption of bacteria to roots as related to host specificity in the Rhizobium-clover symbiosis

Quantitative microscope techniques were utilized to examine the adsorption of rhizobial cells to clover root hairs. Adsorption of cells of noninfective strains of Rhizobium trifolii or infective R. meliloti strains to clover root hairs was four to five times less than that of the infective R. trifolii strains. Attachment of the rod-shaped bacteria to clover root cells occurred in a polar, end-on fashion. Viable or heat-killed R. trifolii cells precoated with a clover lectin having 2-deoxyglucose specificity had increased adsorption to clover roots. Adsorption of bacteria to roots was not increased if the clover lectin was inactivated by heat or 2-deoxyglucose treatment prior to incubation with R. trifolii. Adsorption of R. trifolii to clover root hairs was inhibited by 2-deoxyglucose (30 mM) but not by 2-deoxygalactose or alpha-D-glucose. Adsorption of R. meliloti cells to alfalfa root hairs was not affected by 2-deoxyglucose at that concentration. These results suggest that expression of host specificity in the Rhizobium-clover symbiosis involves a preferential adsorption of infective cells to clover root hairs through a 2-deoxyglucose-sensitive receptor site.     

A class of collocation methods for numerical integration of initial value problems

For the numerical solution of initial value problems a general procedure to determine global integration methods is derived and studied. They are collocation methods which can be easily implemented and provide a high order accuracy. They further provide globally continuous differentiable solutions. Computation of the integrals which appear in the coefficients are generated by a recurrence formula and no integrals are involved in the calculation. Numerical experiments provide favorable comparisons with other existing methods.     

Fenton and photo-Fenton treatment of a synthetic tannin used in leather tannery: a multi-approach study.

The aim of this work was to compare the behaviour of Fenton and photo-Fenton (UV-A, UV-C) processes to treat synthetic tannin (syntan) used in leather tannery which is one of the most polluting industries, releasing many xenobiotics. Both oxidation processes were performed at pH 3.0 and temperature 40-45 degrees C, which is the original temperature of the re-tanning process, in synthetic solutions containing 100 and 300 mg/L of COD equivalent of syntan. The efficiency of the applied oxidation processes was monitored by chemical oxygen demand (COD), oxidation redox potential (ORP) and aromaticity (UV280) and double bond (UV254) absorbance measurements. Acute toxicity test on Daphnia magna was performed to monitor toxicity in untreated and treated syntan solution. Gas chromatography-mass spectrometry (GC-MS) was applied to identify by-products of partial oxidation occurring in treated samples. The effective ratio of H2O2/FeSO4 for photo-Fenton processes was found to be feasible in terms of reagents used in the process.     

Partial depletion and multiple deletions of muscle mtDNA in familial MNGIE syndrome

OBJECTIVE: To describe the unique combination of partial depletion and multiple deletions of mitochondrial DNA (mtDNA) on muscle DNA analysis of three siblings with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). BACKGROUND: MNGIE is a relatively homogeneous autosomal recessive disorder characterized by gastrointestinal dysmobility, ophthalmoparesis, peripheral neuropathy, mitochondrial myopathy, and altered white matter signal at brain imaging. Muscle multiple mtDNA deletions have been found in about half of the described cases. METHODS: We studied three affected siblings (two were monozygotic twins) born to nonconsanguineous parents. Muscle mtDNA was investigated by quantitative Southern and Slot blot techniques and by PCR analysis. Morphologic confirmation in the muscle tissue was achieved by using in situ hybridization with a mtDNA probe complementary to an undeleted region and by DNA immunohistochemistry. RESULTS: All three patients showed ragged red (RRF) and cytochrome c oxidase-negative fibers, as well as partial deficiency of complexes I and IV. Southern and Slot blot analyses showed mtDNA depletion in all patients. Multiple mtDNA deletions were also detected by PCR analysis. In situ hybridization demonstrated an overall signal weaker than controls, with a relatively higher signal in RRF. Antibodies against DNA showed a decreased cytoplasmic network. CONCLUSIONS: The muscle histopathology and respiratory chain enzyme defects may be accounted for by the decreased mtDNA amount and by the presence of mtDNA deleted molecules; however, relative levels of mtDNA seem to correlate with life span in these patients. The combination of partial depletion and multiple deletions of mtDNA might indicate the derangement of a common genetic mechanism controlling mtDNA copy number and integrity.     

Data driven models for a PEM fuel cell stack performance prediction

The operating principles of polymer electrolyte membrane (PEM) fuel cells system involve electrochemistry, thermodynamics and hydrodynamics theory for which it is not always easy to establish a mathematical model. In this paper two different methods to model a commercial PEM fuel cell stack are discussed and compared. The models presented are nonlinear, derived from a black-box approach based on a set of measurable exogenous inputs and are able to predict the output voltage and cathode temperature of a 5 kW module working at the CNR-ITAE. A PEM fuel cell stack fed with H₂ rich gas is employed to experimentally investigate the dynamic behaviour and to reveal the most influential factors. The performance obtained using a classical Neural Networks (NNs) model are compared with a number of stacking strategies. The results show that both strategies are capable of simulating the effects of different stoichiometric ratio in the output variables under different working conditions.     

Coherent and squeezed vibrations for discrete variable harmonic oscillators

In this work we study different types of coherent and squeezed states for the Charlier, Kravchuk and Meixner oscillators. We calculate the average values of different observables corresponding to the coherent states. We found that the coherent and squeezed states of the Kravchuk oscillator are unstable. There are also coherent and squeezed states that are similar to the coherent and squeezed states of the harmonic oscillator. We have introduced a discrete variable model for the biophoton coherent radiation, and the coherent thermal and squeezed thermal states.     

Local entanglement in a bimodal high- Q cavity: Production and utilization

A new conditional scheme for entangling the two quantized modes of a bimodal high-Q cavity field is presented. We show that, injecting one at time k atoms inside the cavity, it is possible to guide the field toward k-dependent linear combinations of k + 1 bimodal Fock states, each one possessing the same total number of photons. The two simple cases corresponding to the passage of one or two atoms only through the resonator are considered. Their practical feasibility against cavity losses, spontaneous emission and other sources of imprecision of the experimental set-up is discussed. Two examples illustrating the usefulness of and the interest toward the creation of such a local entanglement, are reported. The first one relates the specific features of these bimodal entangled states to the occurrence of a non-classical correlation effect in the dynamics of a two-level atom interacting with the entangled cavity. The second one demonstrates that the peculiar entanglement initially stored in the cavity in accordance with our method, provides an effectively exploitable resource to entangle two spatially separated cavities.     

A DPSK Receiver With Enhanced CD Tolerance Through Optimized Demodulation and MLSE

We experimentally demonstrate that a differential phase-shift keying (DPSK) receiver employing a Mach-Zehnder delay interferometer (MZDI) with a bit delay of less than one bit combined with maximum likelihood sequence estimation can considerably enhance the tolerance to chromatic dispersion (CD). Furthermore, we analyze the impact of sampling phase and optimize the MZDI bit delay for 10.7-Gb/s nonreturn-to-zero (NRZ)-DPSK demodulation. Our investigation shows that a 4000-ps/nm CD tolerance at 2-dB penalty is feasible for 10.7-Gb/s NRZ-DPSK.     

An environment for a Virtual Hypermedia Factory

The Advanced Information System group of the National Research Council (CNR) Computer Science Department at the Cybernetics Institute has become involved in research concerning hypermedia systems in the field of cultural heritage. This activity takes place within the three-year project “An Environment for a Virtual Hypermedia Factory” (VHF). The European Commission funded the project within the 4th RTD Framework, Information Technologies (Multimedia Systems domain). The project aims mainly to develop an integrated environment equipped with services and applications for producing, archiving, and spreading information about cultural heritage, tourism, and publishing through the Internet. This environment encourages content integration by stimulating cooperation among information providers in different but correlated knowledge domains. The paper discusses the Virtual Hypermedia Factory consortium and platform requirements